The present invention is generally directed to Solid Oxide Fuel Cells (SOFC's), and more specifically to reversible SOFC's referred to as Solid Oxide Regenerative Fuel Cells (SORFC's).
As resources on land become depleted, people have began to more actively explore options to exploit resources located under ground or under water. For example, natural resources, such as coal and oil are frequently located under ground or under water. However, exploitation of resources located under ground or under water is difficult because these locations often lack metabolic oxygen and a separate source of power to operate electronic equipment. Thus, humans are often forced to operate in closed environments that lack access to atmospheric air to exploit these resources.
Closed environments often require special features to maintain life and to accomplish desired activities. Oxygen gas is provided for metabolic use. Carbon dioxide is removed from the closed atmosphere. A stored fuel is used to provide energy to produce secondary electrical power. A secondary source of electric power is needed if the primary source of power is lost or the primary source of power has undesirable characteristics, such as noise, during certain desired activities.
In current closed environments, oxygen gas is generated for metabolic needs by electrolyzing water using a portion of the primary source of electrical power. Back up oxygen is stored as a high pressure gas in pressure vessels and as oxygen generating candles. Carbon dioxide is concentrated and stored and then discharged from the closed environment, sometimes violating the desired maintenance of the environment closure.
The byproduct of the water electrolysis is hydrogen gas. Hydrogen is a very difficult gas to store. It can be converted into a more storable compound, but it is often simply discharged, again violating the sometimes desired maintenance of the environment closure (i.e., breaching the closed environment by the exhaust of hydrogen).
Secondary electric energy is provided by rechargeable lead acid batteries. Because these batteries have a low energy density, only limited electric energy can be obtained within the allowed space. Additionally, if the primary power is not available the batteries are recharged from a diesel generator set. Because of the low efficiency of the diesel generator set, the fuel supply is large and the oxygen source is obtained from the air outside the closed environment, once more violating the desired maintenance of the environment closure (i.e., breaching the closed environment by the intake of oxygen).